Written by God

Exodus 32:16 - And the tables were the work of God, and the writing was the writing of God, graven upon the tables.

Exodus 34:1,28 - And he was there with the Lord forty days and forty nights; he did neither eat bread, nor drink water. And he wrote upon the tables the words of the covenant, the ten commandments.

Deuteronomy 4:13 - And he declared unto you his covenant, which he commanded you to perform, even ten commandments; and he wrote them upon two tables of stone.

Deuteronomy 10:4 - And he wrote on the tables, according to the first writing, the ten commandments, which the Lord spake unto you in the mount out of the midst of the fire in the day of the assembly: and the Lord gave them unto me.